Several methods of extracting organic products from vegetable or animal matrices are disclosed in the prior art such as JP 02235997 (Preparation of alga aromas by extraction with supercritical or semi-critical carbon dioxide in the presence of water or alcohol), U.S. Pat. No. 4,675,198 (Extraction of aromas from vegetable products using liquid or supercritical extractors), JP 62036178 (Extraction and separation of organic compounds of grape skin), DE 2737794 (Decaffeinisation of coffee by extraction with a solvent), DE 2638383 (Elimination of caffeine from coffee). There are also a significant number of publications which disclose similar processes, although it should be borne in mind that these processes follow the strategy of using supercritical CO.sub.2 in the presence of small amounts or organic and/or inorganic solvents.
A process for the extraction of oils from oil-containing solid vegetable material by means of a mixture consisting of a supercritical gas and a subcritical entraining agent is disclosed in U.S. Pat. No. 5,210,240, herein incorporated by reference.
There are many disadvantages with the current methods, such as the need to use large equipment and a high level of energy to produce relatively small amounts of product. This is because solvents are used with small solubilities or solvents which are not saturated when leaving the extractor as a result of the slow kinetics of extraction involved, and therefore the consumption of solvent per unit of extracted active product mass, is very high.
With current techniques, substances are being extracted from vegetable matrices with pure or modified supercritical CO.sub.2 with a small proportion of organic solvent (ethanol, acetone, hexane, methanol, water, etc.), which is always in a proportion less than 50%.